1. Field of the Invention
The present invention relates to a printing method, and an apparatus for effecting such method. More particularly, the invention is concerned with a method for printing any desired images such as characters, letters, designs, patterns, and so forth on an object having a convex or raised surface, and an apparatus for use in such printing.
2. Description of Prior Art
From U.S. Pat. No. 3,756,165, it has already been known to transfer a picture image onto an object to be printed. The patented method comprises disposing a flexible membrane and a flexible carrier having thereon a picture image to be transferred in a mutually parallel and closed relationship, and then bulging out the flexible membrane like a balloon by an air pressure so as to cause the flexible carrier to intimately contact with the object, onto which raised surface the picture image is to printed, by the pressure exerted at the time of expansion of the flexible membrane.
While the above-mentioned printing method may be suitably adopted for printing an image onto an inner surface of an object having a relatively gentle concave surface such as, for example, dishes, plates, and the like, it is not suitable for printing on an outer surface of an object of a large size and having a steep convex or raised surface (or a three-dimensional curvature) such as, for example, a fuel tank of a motor-cycle or any other large-sized vessels or contains of such configuration. The reason for the inapplicability is that, in the case of causing the flexible carrier to intimately contact with a steep convex surface of a wide area by a pressure of expanded flexible membrane, the flexible carrier is stretched by expansion or bulging out of the flexible membrane at the foot of the convex surface to result in positional discrepancy in the image as transferred thereon, while there takes place not so remarkable discrepancy in the image as transferred onto the top portion of the convex surface. Also, according to the image printing onto the convex surface by the above-described method, there has been another problem such that no sufficient pressure for the image transfer cannot be obtained due to stretching of the fliexible membrane and the flexible image carrying medium.